History of London Wall
Immediately to the north of the Tower of London stands one of the most substantial and impressive surviving sections of the Roman wall around the city of London.
From its earliest foundation the Roman city of Londinium was almost certainly surrounded by some kind of fortification. As well as providing defence, the construction of a stone wall represented the status of the city. Using the evidence of excavated coins, archaeologists have dated the construction of the first stone city wall to between ad 190 and 225.
The wall was about 2.5 miles (4 kilometres) long, enclosing an area of about 330 acres (134 hectares); it originally included four city gates with an additional entrance into the legionary fortress at Cripplegate. In front of the eastern face of the wall was a ditch, which was up to 6 feet (1.8 metres) deep and 16 feet (4.8 metres) across.
This section of the wall stood close to the south-east corner of the ditch, now lying inside the bailey of the Tower of London. It is built of rubble (mostly Kentish ragstone) bound in a hard mortar, and faced on either side by roughly squared ragstone blocks. At every fifth or sixth course the wall incorporates a horizontal band of red Roman tiles, intended to ensure the courses remained level over long stretches of masonry. This gives the wall its distinctive striped appearance. This section shows signs of medieval alteration, particularly in its upper portions, and its original height is unknown; but at about 35 foot (10.7 metres) above present ground level it is one of the tallest surviving sections parts of the circuit.
The wall was originally built without the external D-shaped bastions or turrets which can be seen in several places around the city: these were added in the 4th century AD, almost certainly as emplacements for catapults or stone-throwing engines. One of these bastions, immediately to the north of the standing section of wall, has been found to incorporate reused stonework. This includes parts of a monument bearing the inscription of Julius Alpinus Classicianus, procurator of Britain, who was responsible for the reconstruction of London after the chaos of Boudicca’s rebellion of AD 60 and its violent aftermath.
The dismantling of this monument indicates the urgency with which the wall was strengthened in the later Roman period. The reconstructed Classicianus monument is now displayed in the British Museum, although a replica can be viewed on the site.
The Roman wall remained standing after the departure of the Roman army in AD 410, through a long period during which the city seems to have been largely abandoned. It was repaired in the late Anglo-Saxon period and survived to be an important feature of the city plan at the time of the Norman Conquest of 1066. Large parts of the wall were incorporated into the medieval defences of the city.
In about 1300 a new postern gateway through the wall was built immediately to the south of the standing portion, close to the edge of the Tower of London moat; it later slipped down the moat bank and can be seen at the end of the underpass under the main road.
The Roman wall continued to influence the development of the city street plan through the Middle Ages and beyond. By the mid-17th century buildings had been erected against sections of the wall on either side. In time it was obscured and, later, partly destroyed during the construction of new buildings and railway lines.
In 1938 the wall and part of the land on its western side were placed in the guardianship of the Ministry of Works. Since the 1930s several buildings which had formerly hidden this section of the wall have been cleared away, revealing it to view.
Milne, G, Roman London (English Heritage, London, 1995)